Answer:
Egocentrism
Step-by-step explanation:
Egocentrism involves an individual believing his/her views are the most significant and those of others are irrelevant.
Marcy is said to have been given her choice of two Hershey bars, one of which has been broken into four pieces, and one that is intact and she chooses the broken candy bar, believing that it has more candy when the bars are known to contain the same amount of contents explains egocentricity.